v0.15.5: Disaster recovery — Hub-based infra backup, auto-mount, restore UI

Complete DR implementation (TASK2.md Phases 1-4):
- Hub infra-backup push/pull endpoints (controller.yaml, disk layout, stacks)
- Fresh-deployment detection pulls config from Hub, auto-mounts drives by UUID
- Full-page restore UI with drive status, app table, sequential restore
- docker-setup.sh shows DR instructions when customer_id is configured

New files: disk_layout.go, restore_scan.go, restore_app_linux.go,
restore_drives_linux.go, infra_backup.go, infra_pull.go,
handler_restore.go, restore.html

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/report/pusher.go

@@ -82,6 +82,49 @@ func (p *Pusher) Push(report *Report) error {
 	return fmt.Errorf("hub push failed after 3 attempts: %w", lastErr)
 }
 
+// PushInfraBackup sends the infrastructure backup payload to the Hub.
+// Uses the same retry logic as Push.
+func (p *Pusher) PushInfraBackup(data []byte) error {
+	if !p.enabled {
+		return nil
+	}
+
+	url := p.hubURL + "/api/v1/infra-backup"
+
+	var lastErr error
+	for attempt := 0; attempt < 3; attempt++ {
+		if attempt > 0 {
+			time.Sleep(5 * time.Second)
+		}
+
+		req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(data))
+		if err != nil {
+			lastErr = err
+			continue
+		}
+		req.Header.Set("Content-Type", "application/json")
+		if p.apiKey != "" {
+			req.Header.Set("Authorization", "Bearer "+p.apiKey)
+		}
+
+		resp, err := p.httpClient.Do(req)
+		if err != nil {
+			lastErr = err
+			continue
+		}
+		io.Copy(io.Discard, resp.Body)
+		resp.Body.Close()
+
+		if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+			p.logger.Printf("[INFO] Infra backup pushed to Hub (%d bytes)", len(data))
+			return nil
+		}
+		lastErr = fmt.Errorf("HTTP %d", resp.StatusCode)
+	}
+
+	return fmt.Errorf("infra backup push failed after 3 attempts: %w", lastErr)
+}
+
 // PushOnce sends a single report regardless of the enabled flag.
 // Used for one-time notifications (e.g., reporting-disabled on startup).
 func (p *Pusher) PushOnce(report *Report) error {